First of all i wanted to point out that there is quite a bit of false information in the turbo faq thread, although there is some really good information in there. First thing is that you CAN run more than 5-6 lbs. of boost on stock bottom end, im running 15 lbs on pump gas(93 octane) and could run more probably and ive heard of other people whose done it too. The biggest thing is your timing and fuel. I hear that our stock pistons are our weak point, which they could be but there not as weak as people make them out to be. In my opinion as long as your pretty conservative on timing and KNOW how much timing you can run per boost levels and have good air/fuel numbers you can squeeze quite of bit of power out of these stock motors. I have yet to dyno mine but i would estimate im making around 240 whp on STOCK motor. I ran 13.60 with a slipping ass clutch, could easily run 12's on the stock motor. I think the people who say the motors are weak are people who failed and blew there motor because they didnt know how to tune there own car, so they give out false info to new people who may be thinking of turboing there a20.
Now to get into the tuning of the stock fuel injected system and timing of the vacuum advance distributor. Yes it definately would be better to do obd1 or megasquirt, but if your like me and dont have much money, you figure out ways to make things work. There is no right or wrong way, there are better ways yea, but if it works then how is it wrong. Ive daily driven mine for 2-3 years now and the only problems i have had has been self inflicted by trial and error. Im use a rising rate fmu, you can get pretty cheap off ebay. I got one of the cheaper ones and modified it so that i can change the ratio of how much fuel it adds, just by changing the size of the washer inside of it. Yes it does run higher fuel pressure, but i havent had no problems whatsoever out of it. The FMU with some bigger injectors (im using 390cc junkyard injectors out of automatic dsm) and an adjustable fuel regulator from ebay and thats all you need for the fueling. Keep in mind though you will need a wide band o2 sensor and do a bunch of trial and error and monitoring the wideband guage to get your fuel right. As for timing the vacuum advanced distributor, everyone says you cant do much with them, which is false information. First get a adjustable timing light gun, unplug both vacuum lines from the distributor, retard your distributor all the way, point your gun at the flywheel and rev the car over 4500 rpms and see where your timing is, this will be your full advanced timing, it wont advance any further from this point. Mine was at like 22 or 23 degrees and i was running 12 lbs of boost on that timing. but to run more boost u have to retard it more, in which you cannot turn the distributor anymore, so take the vacuum advance actuator off the distributor and adjust the rod accordingly so it wont advance as much, again this is trial and error, put it back on the distributor and put the timing gun on it again. Right now im running 15 lbs of boost with 18 degrees of full timing. And yea it does lower your overall timing throughout your whole rpms but it works, i just wouldnt go any lower than 15 degrees of full timing because then your timing will be really retarded while your just driving around and everything will be super hot and turbo will be glowing red. Again this isnt the most effective way of tuning your car but it works and is really cheap. Doing it this way will make your lower end torque suffer a little but i dont notice much difference really, its still driveable.
I have blown my motor 3 times testing the limits of timing and boost levels with this motor and have had it back up and running the next day. Basicly i was seeing how much i could get out of it, and theres still more to be had out of the stock A series, but im pretty content with where its at. Im sure ill get flamed for what im about to say but whatever... each time i blew my motor i figured out which piston or pistons blew and i went to the junkyard and pulled a used piston and ring and stuck it in my motor for 15 dollars. Worked just fine everytime. And keep in mind the reason i blew my motors was because i was testing the limits of my stock motor. Ive been driving for a year straight now with a junkyard piston in my motor on 15 lbs.
I have figured out i can run 12 lbs. (on my turbo, super 60 with smaller exhaust housing) without modifying the distributor, but just retarding it as far as it will turn(roughly 23 degrees full timing). And also i can and am running 15 lbs.of boost with my distributor modified to 18 degrees full timing, and have had it to 18 lbs of boost with race gas on the same 18* timing.
You can make good power by doing this cheap setup i have explained, but you wont beable to make 500 hp if thats what your after. But easily have a 12 second Aseries, but then you might have to worry about breaking trannys or axles.
PS.....Keep in mind 15 lbs on one size of turbo can or will make different power than 15 lbs on another size turbo(for those who may read this and not know).
Im not saying if you make a turbo setup, you can do exactly what i did and it work, because your setup will more than likely be different.
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Originally Posted by CAH
that makes it hard to put on a bullet list.
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